JPS63284747A - Sample image display device - Google Patents

Abstract

PURPOSE:To facilitate comparison of an ideal pattern with an actual sample image for improving workability by drawing up the ideal pattern to be formed on a sample surface and displaying the image of the ideal pattern superposed over the sample image on a screen or in another position on the screen. CONSTITUTION:The display device in the caption is provided with a design pattern drawing up means 21 and 2 frame memory 23 for displaying an ideal pattern 40 obtained by the design pattern drawing up means 21 on a CRT indicator 18. The design pattern drawing up means 21 receives input of design data stored in a magnetic tape 22 or the like used for drawing up an actual pattern 30 on an observation sample 9 and draws up a design pattern 40 serving as the ideal pattern formed on the observation sample 9 from the above design data. Thereby, since the design pattern 40 is displayed by being superposed on the actual pattern 30, any observer can immediately understand the relationship between the actual pattern 30 and the design pattern 40 and make comparative observation on both patterns very easily.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a sample image display device used in an apparatus such as a scanning electron microscope.

(Prior art) Conventionally, when it is desired to compare the correspondence between an IC pattern designed using CAD, etc. and an actual IC pattern formed on a semiconductor wafer based on the design values, scanning is used. First, a photo of the sample is taken with a device such as a type electron microscope, and a design pattern is written on the photo, or the photo of the sample is compared with a design pattern drawn on another piece of paper.

In addition, if you are trying to observe a specific pattern formed on a semiconductor wafer using a scanning electron microscope and cannot find the pattern, lower the magnification of the electron microscope used for VA observation and Diagrams and CRT
While constantly comparing the sample images displayed on the screen, move the stage and gradually increase the magnification of the microscope. I was looking for a pattern that I wanted to understand.

(Problems to be Solved by the Invention) However, in such conventional test F4 image inspection, writing a design pattern on a photograph of a specimen taken with an electron microscope, etc. requires The magnification on the photographic paper must be accurately measured, and enlarging or reducing a design pattern with a complex shape to match that magnification is a difficult task. In order to fill in the information accurately, the position of the photographed sample from the chip origin must be determined in advance from the amount of movement of the stage, etc.

The work of emblazoning a design pattern on a photograph of such a successful sample is a difficult work that requires careful attention and a considerable amount of time even if performed by a highly skilled person.

In addition, the task of searching for the desired pattern by moving the stage while comparing the drawing with the design pattern and the sample image displayed on the CRT requires changing the viewpoint many times, which places a heavy burden on the operator. This problem happened very often.

(Means for Solving the Problems) The present invention has been made in view of such conventional problems, and it facilitates comparative observation of an ideal pattern (design pattern) based on design values and an actual sample image. An object of the present invention is to provide a sample image display device that improves workability.

To achieve this objective, the present invention includes an electron optical system that two-dimensionally scans an area on a sample surface with a charged particle beam such as an electron beam, and a secondary A scanning type comprising a display device that sweeps and displays a sample image on a cathode ray tube or the like (CRT) in synchronization or equivalently with the scanning of the sample surface by the charged particle beam based on signals such as electrons or reflected electrons. In equipment such as electron microscopes,
a pattern creation means (21) for creating an ideal pattern to be formed on the sample surface based on design values of the observation sample; Pattern display means (23, 18) for displaying the ideal pattern image obtained by the creation means (21)
> and : are provided.

(Function) In the sample image display device of the present invention having such a configuration, an ideal pattern image (design pattern image) consisting of a line drawing etc. obtained from the design values of the sample is superimposed on the sample image on the CRT. The ideal pattern image corresponding to the sample image can be easily and easily displayed on the CR7 screen and compared with the sample image whenever necessary. I can do it.

(Example) FIG. 1 is an explanatory diagram showing an example of the present invention using a scanning electron microscope as an example.

In FIG. 1, 1 is an electron gun, 2 and 4 are apertures for limiting the electron beam, 3 is a plunker, 5 is a deflector for the X direction, 6 is a deflector for the Y direction, 7 is an objective lens, and 8 1 is a detector, 9 is an observation sample, 10 is a stage, 11 is an electron gun control circuit, 12 is a blanking control circuit, 13 is an XY scanning signal generation circuit, 14 is an X direction scanning signal amplification circuit, and 15 is a Y direction scanning signal amplification circuit. circuit, 16 is an objective lens control circuit,
17 is an image signal amplification circuit, 18 is a CRT display, 19 is a stage drive circuit, 20 is a visual field movement indicator using a joystick lever, trackball, etc., and 24 is an integrated control for the several electric circuits mentioned above. It is a central control circuit.

The structure of the scanning electron microscope having such a structure will be explained in more detail along with its operation as follows.

The electron beam emitted from the electron gun 1 and passed through the apertures 2 and 4 is deflected by the X and Y direction deflectors 5.6.
After being deflected in this direction, it is focused by the objective lens 7 and hits the observation sample 9. At this time, secondary electrons or reflected electrons generated from the observation sample 9 enter the detector 8 and are converted into electrical signals.

The detection signal from the detector 8 is transmitted to the image signal amplification circuit 17
The sample image is amplified to the level required for input to the CRT display 18, and the sample image is displayed in a sweep manner on the CRT display 18 using the horizontal and vertical 1 suspension signals output from the XY scanning signal generation circuit 13. .

On the other hand, the XY scanning signal generation circuit 13 generates horizontal and vertical scanning signals @H and V consisting of two types of sawtooth wave sweep signals that drive the horizontal and vertical deflectors in the CRT display 18, and the Generate scanning signals X and Y to drive the Y-direction deflector 5.6, and drive the CRT display 18 and X, Y, respectively.
The signal is sent to direction scanning signal amplification circuits 14 and 15.

Scanning signal X from the XY scanning signal generation circuit 13.

Y is amplified by an X- and Y-direction scanning signal amplification circuit 14.15 to an amplitude corresponding to the observation magnification of the electron microscope, and drives an X-direction and Y-direction deflector 5.6. Of these electronic circuits,
Some of them receive and take necessary data from the central control circuit 24 to perform optimal control according to the acceleration voltage of the electron gun, observation magnification, etc.

In addition to the scanning electron microscope having such a configuration, the present invention includes a design pattern creation means 21 and an ideal pattern (design pattern) obtained by the design pattern creation means 21 that is displayed on the CRT display 18. It has 71 norm memory 23 for.

The design pattern creation means 21 receives input of design data stored in a magnetic tape 22 or the like used to form an actual pattern on the observation sample 9, and generates an ideal pattern to be formed on the observation sample 9 from this design data. Design as a pattern Create a pattern.

That is, the design pattern creation means 21 receives the stage drive signal from the visual field movement indicator 20, the absolute position coordinates of the stage, and the X-direction and Y-direction scanning signal amplification circuit 14.
The data necessary to display the design pattern, such as magnification information determined by the amplification factor set to 15, is stored in the central control circuit 24.
As a result, the design pattern creation means 21 calculates the design data obtained from the magnetic tape 22 according to set parameters such as the observation magnification of the electron microscope and the observation position on the wafer, and displays the data on the CR7 display. Image data of the design pattern is created as a line drawing at the same magnification and position as the sample image on 18, and written into the frame memory 23 as a bit pattern.

The frame memory 23 is given horizontal and vertical synchronization signals H and V from the XY scanning signal generation circuit 13, and the bit pattern representing the design pattern written in the frame memory 23 is applied to the horizontal and vertical synchronization signals H and V. It is read out synchronously and supplied to the CRT display 18, for example,
As shown in the figure, the crotch δ1 pattern 40 is displayed superimposed on the actual pattern 30 as the sample image.

As is clear from the display example in FIG. 2, the display screen of the CRT display 18 displays images obtained based on design data superimposed on the actual pattern 30 as a sample image obtained by a scanning electron microscope. 40 design patterns as ideal patterns
is displayed, the observer can immediately understand the relationship between the actual pattern 30 and the designed pattern 40, and can very easily compare and observe the two.

Further, the display of the design pattern 40 can be turned on and off at any time by a switch on the operation panel, and when it is not necessary, only the sample image can be displayed by turning off the switch. Furthermore, when the sample image is moved by operating the field of view movement indicator 20, the design pattern is automatically moved in conjunction with the movement of the sample image, and the design pattern is always at the same position regardless of the movement of the sample image. By providing a mode selection function for a fixed mode in which the design pattern is displayed, visual observation of the sample image and the design pattern can be made easier.

That is, in the fixed mode, the design pattern to be observed is displayed, and in this state, only the sample images are moved one after another using the field of view movement indicator 20, so that the same sample image as the design pattern can be found. This makes it easier to search for the sample image you want to observe.

Furthermore, in the fixed mode, move the actual pattern so that it overlaps with the design pattern and align it, then switch to the interlocking mode and move the sample image and the design pattern by the same distance to see how it overlaps with another pattern. Since it is possible to check the positional deviation in the long dimension due to the difference in length, it is very effective when applied to a scanning electron microscope with a length measurement function.

Note that the above embodiment takes the case where the design pattern is displayed superimposed on the sample image (actual pattern), but the sample image on the display screen is displayed without superimposing the design pattern on the sample image. It may be displayed in a different position.

(Effects of the Invention) As explained above, according to the present invention, an ideal pattern (design pattern) to be formed on the sample surface is created based on the design data used for pattern formation of the observation sample, and Since the ideal pattern image (design pattern image) is displayed superimposed on the image or at a different position on the screen, the viewer can compare the design pattern and the actual pattern formed on the semiconductor wafer on the CR7 screen as needed. As a result, distortions and defects that occur during the pattern formation process can be easily observed from the comparison of the two, and comparisons can be made by photographing the actual pattern or by comparing the design with the photographed actual pattern. Since work such as writing patterns is not required, the observation work of comparing the designed pattern and the actual pattern becomes extremely easy, and it is possible to improve workability and significantly reduce operator fatigue.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing one embodiment of the present invention using a scanning electron microscope as an example, and FIG. 2 is an illustration of an actual pattern according to the present invention (
FIG. 3 is an explanatory diagram showing a display example of a sample image and a design pattern (ideal pattern). 1: Electron gun 2.4 Near aperture 3 Nib blanker 5: Deflector for x direction 6: Deflector for Y direction 7: Objective lens 8: Detector 9: Observation sample 10: Stage 11: Electron gun control circuit 12 Nib blanking control circuit 1a :x? Scanning signal generation circuit 14: X-direction scanning signal Clothing circuit 15: Y-direction scanning signal amplification circuit 16 Two-objective lens control circuit 17: Image signal amplification circuit 19: Stage drive circuit 20: Visual field movement indicator 21: Design pattern creation means 22: Magnetic tape 23: Frame memory 24: Central control circuit 30: Actual pattern (sample image)

Claims (1)

[Claims] An electron optical system that two-dimensionally scans an area on a sample surface with a charged particle beam such as an electron beam, and signals such as secondary electrons or reflected electrons obtained from the sample by irradiation with the charged particle beam. In an apparatus such as a scanning electron microscope, which is equipped with a display device that sweeps and displays a sample image on a cathode ray tube or the like (CRT) in synchronization with the scanning of the sample surface by the charged particle beam or equivalently in synchronization with the scanning of the sample surface by the charged particle beam. a pattern creating means for creating an ideal pattern formed on a sample surface based on design values of the observation specimen; A sample image display device comprising: a pattern display means for displaying an ideal pattern image obtained by the means;